一种硼掺杂多孔碳球的制备方法Method for preparing boron-doped porous carbon sphere
技术领域Technical field
本发明涉及一种硼掺杂碳材料的制备方法,特别涉及一种硼掺杂多孔碳球的合成方法。The invention relates to a preparation method of a boron-doped carbon material, in particular to a method for synthesizing a boron-doped porous carbon sphere.
背景技术Background technique
在各种电化学能量储存装置或设备中,锂离子电池由于其较高的能量密度及长循环寿命,在手机及电动汽车领域已得到广泛应用,面对日益增长技术需求,下一代高性能锂离子电池要求具有更高的倍率性能及循环稳定性,特别是对负极材料的要求。目前商用的负极材料为石墨,其较低的理论容量(372mAh g-1)及倍率性能是现在目前锂离子电池性能的关键。因此,国内外研究学者提出了各种具有高锂离子储存容量的负极替代材料,如Sn,SnO2,Si,ZnO及各种过渡金属氧化物。然而,上述材料在电化学嵌锂脱锂过程均存在体积变化严重、电极材料与电解液副反应严重以及电极材料化学稳定性差等问题,从而限制了锂离子负极材料的倍率性能及循环寿命。Among various electrochemical energy storage devices or devices, lithium-ion batteries have been widely used in mobile phones and electric vehicles due to their high energy density and long cycle life. In the face of increasing technology demand, next-generation high-performance lithium Ion batteries are required to have higher rate performance and cycle stability, especially for anode materials. At present, the commercial anode material is graphite, and its lower theoretical capacity (372 mAh g -1 ) and rate performance are the key to the current performance of lithium ion batteries. Therefore, domestic and foreign researchers have proposed various anode replacement materials with high lithium ion storage capacity, such as Sn, SnO 2 , Si, ZnO and various transition metal oxides. However, in the electrochemical lithium intercalation process, there are problems such as serious volume change, serious reaction between the electrode material and the electrolyte, and poor chemical stability of the electrode material, thereby limiting the rate performance and cycle life of the lithium ion anode material.
相比较而言,碳基材料,特别是多孔碳材料,具有高化学稳定性及丰富的孔隙结构,作为锂离子电池负极材料,能够利用其丰富的孔隙结构及大的比表面积对锂离子进行吸附储存,从而相比于石墨具有大大提高的锂离子储存容量。相关研究发现,对碳基材料进行杂原子掺杂(如氮掺杂、硼掺杂)可进一步提高锂离子负极材料的容量、倍率性能及循环稳定性。其中,硼元素掺杂一方面可增强碳材料内部锂离子储存的吸附位点,从而提高锂离子储存容量;另一方面可在碳骨架结构能引入高化学稳定性的BC3、BC2O以及BCO2等含硼结构单元,从而大大提高碳材料在电化学反应中的结构稳定性,特别是在大电流密度下的循环稳定性。In comparison, carbon-based materials, especially porous carbon materials, have high chemical stability and rich pore structure. As a negative electrode material for lithium ion batteries, they can utilize the abundant pore structure and large specific surface area to adsorb lithium ions. It is stored to have a greatly increased lithium ion storage capacity compared to graphite. Related studies have found that heteroatom doping (such as nitrogen doping and boron doping) of carbon-based materials can further improve the capacity, rate performance and cycle stability of lithium ion anode materials. Among them, boron doping can enhance the adsorption site of lithium ion storage inside the carbon material, thereby increasing the storage capacity of lithium ions; on the other hand, it can introduce BC 3 and BC 2 O with high chemical stability in the carbon skeleton structure. Boron-containing structural units such as BCO 2 greatly improve the structural stability of carbon materials in electrochemical reactions, especially at high current densities.
现有技术中关于硼掺杂多孔碳材料或硼掺杂石墨烯材料的制备方法包括化学气相沉积法、硼源后处理方法以及硼源与碳源共水热合成法。目前硼掺杂碳基材料的制备方法均存在原料成本高,制备工艺耗时、繁琐且难以规模化批量生产以及硼掺杂含量低(<4-wt%)等问题。为弥补上述提及制备方法的不足,本发明要解决的技术问题是提供一种工艺简单、可实现原位硼元素掺杂且具有规模化放大生产潜力的硼掺杂多孔碳球的制备
方法。The preparation methods of the boron-doped porous carbon material or the boron-doped graphene material in the prior art include a chemical vapor deposition method, a boron source post-treatment method, and a co-hydrothermal synthesis method of a boron source and a carbon source. At present, the preparation methods of the boron-doped carbon-based materials have the problems of high raw material cost, time-consuming preparation, cumbersome and difficult mass production, and low boron doping content (<4-wt%). In order to make up for the deficiencies of the above-mentioned preparation methods, the technical problem to be solved by the present invention is to provide a preparation of boron-doped porous carbon spheres with simple process, in-situ boron doping and large-scale amplification production potential.
method.
发明内容Summary of the invention
本发明提供的硼掺杂多孔碳球制备方法是为了解决目前硼掺杂碳材料了技术存在的高成本、硼掺杂量低以及难以规模化生产的问题,以硼酸、糖类、硅基造孔剂为硼源、碳源及孔隙模板通过喷雾干燥工艺辅助的自组装过程,得到硼掺杂多孔碳球。The preparation method of the boron-doped porous carbon sphere provided by the invention is to solve the problems of high cost, low boron doping amount and difficult scale production of the current boron doped carbon material technology, and is made of boric acid, sugar and silicon. The pore agent is a boron source, a carbon source and a pore template which are assisted by a spray drying process to obtain a boron-doped porous carbon sphere.
本发明的制备机理及关键构思在于:利用硼酸中羟基和糖类中羟基间的自组装作用,形成硼掺杂碳的前驱体溶液;为创造孔隙,在上述前驱体溶液中加入能够与硼酸及糖类物质形成良好络合作用的硅基造孔剂;以上前驱体溶液经过(气溶胶辅助)喷雾干燥过程形成多分散的纳米球体,与此同时,硼源、碳源及造孔剂形成的气溶胶液滴发生溶剂蒸发引导的自组装反应及初步缩聚反应形成固体球体;再经过高温热解过程及孔模板去除过程得到硼元素原位、高含量掺杂的多孔碳球。从上述描述可知,本发明的得到的硼掺杂多孔碳球可实现多方面结构性能的调控和优化,包括外部形貌(可实现多分散纳米球体的连续制备)、孔隙结构(可通过孔模板的选择及比例调控实现)、硼掺杂量(可通过前驱体溶液中硼酸的比例调控实现)。此外,低成本的原料选择及简单连续的生产工艺使本发明得到的硼掺杂多孔碳球在锂离子电池负极材料中具有重要应用潜力。The preparation mechanism and the key idea of the present invention are: forming a precursor solution of boron-doped carbon by self-assembly between hydroxyl groups in a boric acid and a hydroxyl group in a saccharide; in order to create pores, a boric acid can be added to the precursor solution and The saccharide material forms a silicon-based pore former for good complexation; the above precursor solution undergoes (aerosol-assisted) spray drying process to form polydisperse nanospheres, and at the same time, a boron source, a carbon source and a pore former are formed. The aerosol droplets undergo solvent evaporation-induced self-assembly reaction and preliminary polycondensation reaction to form solid spheres; and then high-temperature pyrolysis process and pore template removal process to obtain boron-based in-situ, high-content doped porous carbon spheres. It can be seen from the above description that the obtained boron-doped porous carbon sphere of the present invention can realize the regulation and optimization of various structural properties, including external morphology (continuous preparation of polydisperse nanospheres can be realized), pore structure (through pore template) The choice and proportional control implementation), boron doping amount (can be achieved by the proportional regulation of boric acid in the precursor solution). In addition, the low-cost raw material selection and the simple continuous production process make the boron-doped porous carbon sphere obtained by the invention have an important application potential in the lithium ion battery anode material.
本发明的具体技术方案为:The specific technical solution of the present invention is:
提供一种硼掺杂多孔碳球的制备方法,包括以下步骤:A method for preparing a boron-doped porous carbon sphere is provided, comprising the steps of:
(1)将糖类碳源与硼酸(硼源)溶于水中以一定比例混合、搅拌为透明溶液;(1) dissolving a sugar carbon source and boric acid (boron source) in water at a certain ratio and stirring into a transparent solution;
(2)将硅基造孔剂加入步骤(1)中溶液中搅拌形成硼掺杂多孔碳球前驱体溶液;(2) adding a silicon-based pore former to the solution in the step (1) to form a boron-doped porous carbon sphere precursor solution;
(3)步骤(2)所得的前驱体溶液经过(气溶胶辅助)喷雾干燥过程,前驱体溶液在喷雾及热处理过程中发生羟基引导自组装及缩聚过程得到固态硼掺杂碳球前驱体颗粒;(3) The precursor solution obtained in the step (2) is subjected to an (aerosol assisted) spray drying process, and the precursor solution is subjected to a hydroxyl-guided self-assembly and polycondensation process during the spraying and heat treatment to obtain a solid boron-doped carbon sphere precursor particle;
(4)步骤(3)所得固体颗粒在惰性气氛中加热至600~1000℃,得到孔隙模板SiO2嵌入掺硼碳球的混合物;(4) The solid particles obtained in the step (3) are heated to 600 to 1000 ° C in an inert atmosphere to obtain a mixture of pore template SiO 2 embedded in the boron-doped carbon spheres;
(5)去除步骤(4)所得混合物中的硅基造孔剂,得到硼掺杂多孔碳球。(5) The silicon-based pore former in the mixture obtained in the step (4) is removed to obtain a boron-doped porous carbon sphere.
优选的,所述糖类碳源选自葡萄糖、蔗糖、麦芽糖、壳聚糖和可溶性淀粉中的一种或几种,硼酸与糖类的质量比为0.1∶100~1∶1。Preferably, the saccharide carbon source is one or more selected from the group consisting of glucose, sucrose, maltose, chitosan and soluble starch, and the mass ratio of boric acid to saccharide is from 0.1:100 to 1:1.
优选的,所述硅基造孔剂选自四乙基正硅酸乙酯(TEOS)、纳米二氧化硅(SiO2)和水玻璃中的一种或几种,硅基造孔剂与糖类的质量比为5∶1~1∶10。
Preferably, the silicon-based pore former is selected from one or more of tetraethyl orthosilicate (TEOS), nano silica (SiO 2 ) and water glass, and the silicon-based pore-forming agent and sugar The mass ratio of the classes is from 5:1 to 1:10.
优选的,所述喷雾干燥过程的加热温度为300~600℃。Preferably, the spray drying process has a heating temperature of 300 to 600 °C.
优选的,所述喷雾干燥过程中的气溶胶为液滴携带气体,所述气体为氮气或氩气中的一种或多种,气体流速为0~50L/min。Preferably, the aerosol in the spray drying process is a droplet carrying gas, and the gas is one or more of nitrogen or argon, and the gas flow rate is 0-50 L/min.
优选的,步骤4)中的惰性气氛为氮气和氩气中的一种或两种。Preferably, the inert atmosphere in step 4) is one or both of nitrogen and argon.
优选的,所述高温热解的加热温度为600~1000℃,加热速率为0.5℃~15℃/min,保温时间为0~6h。Preferably, the high temperature pyrolysis has a heating temperature of 600 to 1000 ° C, a heating rate of 0.5 ° C to 15 ° C / min, and a holding time of 0 to 6 h.
优选的,所述硅基造孔剂的去除采用氢氟酸或氢氧化钠洗涤方式,洗涤液为1%~10%氢氟酸溶液或0.5mol/L~5mol/L氢氧化钠中的一种或几种,洗涤温度为25~60℃,洗涤方式包括离心及抽滤。Preferably, the removal of the silicon-based pore former is performed by using hydrofluoric acid or sodium hydroxide, and the washing liquid is 1% to 10% hydrofluoric acid solution or one of 0.5 mol/L to 5 mol/L sodium hydroxide. Kind or several, washing temperature is 25 ~ 60 ° C, washing methods include centrifugation and suction filtration.
优选的,步骤5)中干燥过程的温度为50~120℃。Preferably, the temperature of the drying process in step 5) is from 50 to 120 °C.
另一方面,本发明还涉及一种采用上述制备方法所制备的硼掺杂的多孔碳球。In another aspect, the present invention is also directed to a boron-doped porous carbon sphere prepared by the above preparation method.
本发明的显著优势表现为:The significant advantages of the present invention are:
(1)本发明以低成本硼酸和糖类为硼源和碳源,相比于现有硼掺杂碳材料制备方法采用的昂贵原料如硼氢化钠、氯化硼等,具有显著经济优势;(1) The present invention uses a low-cost boric acid and a saccharide as a boron source and a carbon source, and has a significant economic advantage compared with the expensive raw materials used in the preparation method of the existing boron-doped carbon material, such as sodium borohydride or boron chloride;
(2)本发明提供发明方法采用(气溶胶辅助)喷雾干燥处理方法,工艺简单,可实现连续化生产,具有显著的工业应用优势;(2) The present invention provides an aerosol-assisted spray drying treatment method, which is simple in process, can realize continuous production, and has significant industrial application advantages;
(3)本发明提供的硼掺杂多孔碳球由分子前驱体自组装反应获得,通过前驱体溶液中碳源、硼源及造孔剂比例的调节可实现硼掺杂量和孔隙结构的调控,从而获得面对不同应用需求的硼掺杂多孔碳球;(3) The boron-doped porous carbon sphere provided by the invention is obtained by molecular precursor self-assembly reaction, and the boron doping amount and pore structure can be controlled by adjusting the ratio of carbon source, boron source and pore former in the precursor solution. , thereby obtaining boron-doped porous carbon spheres facing different application requirements;
(4)本发明方法制备的硼掺杂多孔碳球具有比表面积大、可原位掺硼、硼掺杂量高、结构可控以及碳结构稳定性高等优点,将在锂离子电池领域有重要应用价值。(4) The boron-doped porous carbon sphere prepared by the method of the invention has the advantages of large specific surface area, boron in situ doping, high boron doping amount, structure controllability and high carbon structure stability, and will be important in the field of lithium ion batteries. Value.
附图说明DRAWINGS
图1(a)为实施例1所得硼掺杂多孔碳球的SEM图片;1(a) is a SEM picture of the boron-doped porous carbon sphere obtained in Example 1;
图1(b)为实施例1所得硼掺杂多孔碳球的SEM图片;1(b) is a SEM picture of the boron-doped porous carbon sphere obtained in Example 1;
图1(c)为实施例1所得硼掺杂多孔碳球的TEM图片;1(c) is a TEM image of the boron-doped porous carbon sphere obtained in Example 1;
图1(d)为实施例1所得硼掺杂多孔碳球中C元素分布图;1(d) is a diagram showing the distribution of C elements in the boron-doped porous carbon sphere obtained in Example 1;
图1(e)为实施例1所得硼掺杂多孔碳球中B元素分布图;1(e) is a B element distribution diagram of the boron-doped porous carbon sphere obtained in Example 1;
图1(f)为实施例1所得硼掺杂多孔碳球中O元素分布图;1(f) is a diagram showing the distribution of O elements in the boron-doped porous carbon sphere obtained in Example 1;
图2为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的拉
曼光谱图;2 is a drawing of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1.
Mann spectrum
图3为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的N2吸附等温线。3 is an N2 adsorption isotherm of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1.
图4为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球在空气气氛下的失重曲线。4 is a graph showing the weight loss curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1 under an air atmosphere.
图5为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的X射线光电子能谱(XPS)分峰曲线。5 is a X-ray photoelectron spectroscopy (XPS) peak curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1.
图6为实施例1得到的硼掺杂多孔碳球组成的锂离子电池在0.2mV s-1扫速下的循环伏安特性曲线。6 is a cyclic voltammetric characteristic curve of a lithium ion battery composed of boron-doped porous carbon spheres obtained in Example 1 at a sweep speed of 0.2 mV s -1 .
图7为实施例1得到的硼掺杂多孔碳球组成的锂离子电池在0.2A g-1电流密度下的恒电流充放电曲线。7 is a graph showing a constant current charge and discharge curve of a lithium ion battery composed of boron-doped porous carbon spheres obtained in Example 1 at a current density of 0.2 A g -1 .
图8为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的倍率性能曲线。8 is a graph showing the rate performance curves of the boron-doped porous carbon spheres obtained in Example 1 and the undoped porous carbon spheres obtained in Comparative Example 1.
图9为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的在0.2A g-1电流密度下的循环稳定性曲线。Fig. 9 is a cycle stability curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1 at a current density of 0.2 A g -1 .
图10为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的在大电流密度5A g-1下的循环稳定性曲线。10 is a cycle stability curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1 at a large current density of 5 A g -1 .
具体实施方式detailed description
以下结合附图与具体实施例进一步阐述本发明的优点。Advantages of the present invention are further explained below in conjunction with the accompanying drawings and specific embodiments.
实施例1:Example 1:
本实施例硼掺杂多孔碳球制备方法按下列步骤实现:称取1.8g葡萄糖、1.24g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入4.2g四乙基正硅酸乙酯、2mL 0.1mol/L盐酸、15mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。The preparation method of the boron-doped porous carbon sphere of the present embodiment is achieved by the following steps: weigh 1.8 g of glucose, 1.24 g of boric acid is dissolved in 15 mL of deionized water and stirred until completely dissolved, and 4.2 g of tetraethyl orthosilicate, 2 mL are sequentially added. 0.1 mol/L hydrochloric acid, 15 mL ethanol and stirring for 1 h to form a precursor solution, and then the precursor solution was carried by nitrogen into an aerosol-assisted spray drying device at a temperature of 450 ° C, and controlled to carry a nitrogen gas flow rate of 500 mL / min, the obtained solid product The tube was heated to 900 ° C in nitrogen at a heating rate of 8 ° C / min and held for 3 h. The obtained carbonized product was repeatedly washed with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 h. The boron-doped porous carbon spheres of this example were obtained.
对比实施例1:
Comparative Example 1:
为得到硼掺杂对碳材料结构的影响,本发明提供了未掺杂硼的多孔碳球制备方法:称取1.8g葡萄糖溶于15mL去离子水中搅拌至完全溶解,依次加入4.2g四乙基正硅酸乙酯、2mL 0.1mol/L盐酸、15mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到对比实施例1下的未掺杂多孔碳球。In order to obtain the influence of boron doping on the structure of the carbon material, the present invention provides a method for preparing porous carbon spheres which are not doped with boron: 1.8 g of glucose is dissolved in 15 mL of deionized water and stirred until completely dissolved, and 4.2 g of tetraethyl group is sequentially added. Ethyl orthosilicate, 2mL of 0.1mol / L hydrochloric acid, 15mL of ethanol and stirred for 1h to form a precursor solution, and then the precursor solution was carried by nitrogen into an aerosol-assisted spray drying device with a temperature of 450 ° C to control the flow of nitrogen carrying 500mL /min, the obtained solid product was heated to 900 ° C in a tube furnace at a heating rate of 8 ° C / min under nitrogen for 3 h, and the obtained carbonized product was repeatedly washed by using 10% hydrofluoric acid and deionized water for 3 times. It was then dried at 80 ° C for 10 h to obtain an undoped porous carbon sphere of Comparative Example 1.
实施例2:Example 2:
称取1.8g蔗糖、1.8g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入4.2g四乙基正硅酸乙酯、2mL 0.1mol/L盐酸、15mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为4.5%。Weigh 1.8g sucrose, 1.8g boric acid dissolved in 15mL deionized water and stir until completely dissolved. Add 4.2g of tetraethyl orthosilicate, 2mL of 0.1mol/L hydrochloric acid, 15mL of ethanol and stir for 1h to form the precursor solution. Then, the precursor solution is carried into the aerosol-assisted spray drying device with a temperature of 450 ° C under nitrogen, and the flow rate of the nitrogen gas is controlled to be 500 mL/min. The obtained solid product is heated by a tube furnace at a heating rate of 8 ° C / min in nitrogen. The mixture was heated to 900 ° C for 3 hours, and the obtained carbonized product was repeatedly washed by centrifugation with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 hours to obtain a boron-doped porous carbon sphere of the present example. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 4.5%.
实施例3:Example 3:
称取1.8g可溶性淀粉、1.24g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入4.2g四乙基正硅酸乙酯、2mL 0.1mol/L盐酸、15mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为3.2%。Weigh 1.8g soluble starch, 1.24g boric acid dissolved in 15mL deionized water and stir until completely dissolved. Add 4.2g of tetraethyl orthosilicate, 2mL 0.1mol/L hydrochloric acid, 15mL ethanol and stir for 1h to form the precursor solution. Then, the precursor solution is carried by nitrogen into an aerosol-assisted spray drying device at a temperature of 450 ° C, and the flow rate of nitrogen gas is controlled to be 500 mL/min, and the obtained solid product is heated at a rate of 8 ° C / min in a tubular furnace under nitrogen. The temperature was raised to 900 ° C and kept for 3 hours, and the obtained carbonized product was repeatedly washed with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 hours to obtain a boron-doped porous carbon sphere of the present example. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 3.2%.
实施例4:Example 4:
称取1.8g葡萄糖、1.24g硼酸溶于15mL去离子水中搅拌至完全溶解,加入15g纳米SiO2溶液(溶剂为水,SiO2纳米颗粒尺寸为15~20nm,质量分数为30%)并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥
装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为2.5%。Weigh 1.8g glucose, 1.24g boric acid dissolved in 15mL deionized water and stir until completely dissolved. Add 15g nano-SiO 2 solution (solvent is water, SiO 2 nanoparticle size is 15-20nm, mass fraction is 30%) and stir for 1h. A precursor solution is formed, and then the precursor solution is carried by nitrogen into an aerosol-assisted spray drying device at a temperature of 450 ° C to control a nitrogen gas flow rate of 500 mL/min, and the obtained solid product is subjected to a tube furnace at 8 ° C in nitrogen. The heating rate of min was raised to 900 ° C and kept for 3 h, and the obtained carbonized product was repeatedly washed with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 h to obtain boron-doped porous in this example. Carbon ball. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 2.5%.
实施例5:Example 5:
称取1.8g麦芽糖、1.24g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入4.2g四乙基正硅酸乙酯、2mL 0.1mol/L盐酸、15mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按2℃/min的升温速率升温至600℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为5.3%。Weigh 1.8g maltose, 1.24g boric acid dissolved in 15mL deionized water and stir until completely dissolved. Add 4.2g of tetraethyl orthosilicate, 2mL of 0.1mol/L hydrochloric acid, 15mL of ethanol and stir for 1h to form the precursor solution. Then, the precursor solution is carried into the aerosol-assisted spray drying device with a temperature of 450 ° C under nitrogen, and the flow rate of nitrogen gas is controlled to be 500 mL/min. The obtained solid product is heated by a tube furnace at a heating rate of 2 ° C/min in nitrogen. After heating to 600 ° C for 3 h, the obtained carbonized product was repeatedly washed by centrifugation with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 h to obtain a boron-doped porous carbon sphere of the present example. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 5.3%.
实施例6:Example 6
称取1.8g可溶性淀粉、0.6g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入15g纳米SiO2溶液(溶剂为水,SiO2纳米颗粒尺寸为15~20nm,质量分数为30%)并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至1000℃并保温3h,得到的碳化产物用5mol/L氢氧化钠溶液和去子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为0.8%。Weigh 1.8g soluble starch, 0.6g boric acid dissolved in 15mL deionized water and stir until completely dissolved. Add 15g nano-SiO 2 solution (solvent is water, SiO 2 nanoparticle size is 15-20nm, mass fraction is 30%). The precursor solution was stirred for 1 h, and then the precursor solution was carried by nitrogen into an aerosol-assisted spray drying device at a temperature of 450 ° C to control the flow rate of nitrogen carrying 500 mL/min. The obtained solid product was pressed in a nitrogen tube by a tube furnace. The heating rate of °C/min was raised to 1000 °C and kept for 3 hours. The obtained carbonized product was repeatedly washed with 5 mol/L sodium hydroxide solution and deionized water for 3 times, and then dried at 80 ° C for 10 h to obtain the following example. Boron-doped porous carbon spheres. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 0.8%.
实施例7:Example 7
称取1.8g葡萄糖、1.24g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入4.2g四乙基正硅酸乙酯、2mL 0.1mol/L盐酸、15mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为300℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为1L/min,获得的固体产物用管式炉在氮气中按5℃/min的升温速率升温至800℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量
为3.6%。Weigh 1.8g of glucose, 1.24g of boric acid dissolved in 15mL of deionized water and stir until completely dissolved. Add 4.2g of tetraethyl orthosilicate, 2mL of 0.1mol/L hydrochloric acid, 15mL of ethanol and stir for 1h to form the precursor solution. Then, the precursor solution was carried into the aerosol-assisted spray drying device at a temperature of 300 ° C through nitrogen gas, and the flow rate of the nitrogen gas carried was controlled to be 1 L/min, and the obtained solid product was heated by a tube furnace at a heating rate of 5 ° C / min in nitrogen. The mixture was kept at 800 ° C for 3 hours, and the obtained carbonized product was repeatedly washed with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 hours to obtain a boron-doped porous carbon sphere of the present example. XPS analysis shows the boron content of the boron-doped porous carbon sphere
It is 3.6%.
实施例8:Example 8
称取1.8g蔗糖、1.24g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入8.4g四乙基正硅酸乙酯、4mL 0.1mol/L盐酸、30mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为2.6%。Weigh 1.8g sucrose, 1.24g boric acid dissolved in 15mL deionized water and stir until completely dissolved. Add 8.4g of tetraethyl orthosilicate, 4mL of 0.1mol/L hydrochloric acid, 30mL of ethanol and stir for 1h to form the precursor solution. Then, the precursor solution is carried into the aerosol-assisted spray drying device with a temperature of 450 ° C under nitrogen, and the flow rate of the nitrogen gas is controlled to be 500 mL/min. The obtained solid product is heated by a tube furnace at a heating rate of 8 ° C / min in nitrogen. The mixture was heated to 900 ° C for 3 hours, and the obtained carbonized product was repeatedly washed by centrifugation with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 hours to obtain a boron-doped porous carbon sphere of the present example. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 2.6%.
实施例9:Example 9
称取1.8g葡萄糖、0.9g硼酸溶于15mL去离子水中搅拌至完全溶解,依次加入2.1g四乙基正硅酸乙酯、1mL 0.1mol/L盐酸、8mL乙醇并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为450℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为500mL/min,获得的固体产物用管式炉在氮气中按5℃/min的升温速率升温至1000℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为2.3%。Weigh 1.8g of glucose, 0.9g of boric acid dissolved in 15mL of deionized water and stir until completely dissolved. Add 2.1g of tetraethyl orthosilicate, 1mL of 0.1mol/L hydrochloric acid, 8mL of ethanol and stir for 1h to form the precursor solution. Then, the precursor solution is carried into the aerosol-assisted spray drying device with a temperature of 450 ° C through nitrogen gas, and the flow rate of nitrogen gas is controlled to be 500 mL/min, and the obtained solid product is heated by a tube furnace at a heating rate of 5 ° C / min in nitrogen. The mixture was heated to 1000 ° C for 3 hours, and the obtained carbonized product was repeatedly washed by centrifugation with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 hours to obtain a boron-doped porous carbon sphere of the present example. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 2.3%.
实施例10:Example 10:
称取3.6g蔗糖、3.6g硼酸溶于30mL去离子水中搅拌至完全溶解,加入30g纳米SiO2溶液(溶剂为水,SiO2纳米颗粒尺寸为15~20nm,质量分数为30%)并搅拌1h形成前驱体溶液,然后前驱体溶液经过氮气携带进入温度为500℃的气溶胶辅助喷雾干燥装置中,控制携带氮气流量为2mL/min,获得的固体产物用管式炉在氮气中按8℃/min的升温速率升温至900℃并保温3h,得到的碳化产物用10%氢氟酸和去离子水反复离心洗涤3次,然后在80℃下干燥10h,得到本实施例下的硼掺杂多孔碳球。XPS分析表明该硼掺杂多孔碳球的硼含量为3.8%。Weigh 3.6g sucrose, 3.6g boric acid dissolved in 30mL deionized water and stir until completely dissolved. Add 30g nano SiO 2 solution (solvent is water, SiO 2 nanoparticle size is 15-20nm, mass fraction is 30%) and stir for 1h. A precursor solution is formed, and then the precursor solution is carried by nitrogen into an aerosol-assisted spray drying device at a temperature of 500 ° C to control a nitrogen gas flow rate of 2 mL/min, and the obtained solid product is subjected to a tube furnace at 8 ° C in nitrogen. The heating rate of min was raised to 900 ° C and kept for 3 h, and the obtained carbonized product was repeatedly washed with 10% hydrofluoric acid and deionized water for 3 times, and then dried at 80 ° C for 10 h to obtain boron-doped porous in this example. Carbon ball. XPS analysis indicated that the boron-doped porous carbon spheres had a boron content of 3.8%.
效果实施例:
Effect example:
对实施例1得到的硼掺杂多孔碳球进行结构及性能分析:采用拉曼光谱、扫描电镜、透射电镜、热重分析、低温N2吸附、X射线光电子能谱法等手段对实施例1所得多孔石墨烯材料石墨化度、微观形貌、孔隙结构参数、碳结构稳定性以及硼掺杂量进行详细表征。具体操作如下:The structure and properties of the boron-doped porous carbon spheres obtained in Example 1 were analyzed by Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, low temperature N 2 adsorption, X-ray photoelectron spectroscopy, etc. The graphitization degree, micromorphology, pore structure parameters, carbon structure stability and boron doping amount of the obtained porous graphene materials were characterized in detail. The specific operations are as follows:
以实施例1所得硼掺杂多孔碳球为锂离子电池负极材料,其性能测试方法为:以锂片为对电极,硼掺杂多孔碳球为工作电极活性物质,组装CR2032纽扣电池测试其作为锂离子电池负极材料性能。其中工作电极制备方法为:将硼掺杂多孔碳球、炭黑、和PVDF以7∶1.5∶1.5的质量比溶于NMP并研磨成均一浆料,之后将浆料涂覆在铜箔上并在80℃下真空烘干12h得到工作电极极片。烘干的极片裁剪为圆形片状并保持活性物质密度为0.5~1mg cm-2,与新鲜锂片在手套箱内组装为纽扣电池,电解液为1M LiPF6(溶剂为碳酸亚乙酯和碳酸二乙酯1∶1),Whatman玻璃纤维膜为隔膜。测试电池在0.01~3.0V vs.Li/Li+电压范围内的循环伏安特性曲线及恒电容恒电流充放电曲线。具体分析结果如下:The boron-doped porous carbon sphere obtained in the first embodiment is a negative electrode material for a lithium ion battery, and the performance test method is as follows: a lithium sheet is used as a counter electrode, a boron-doped porous carbon sphere is a working electrode active material, and a CR2032 button battery is assembled to test the same. Lithium ion battery anode material properties. The working electrode is prepared by dissolving boron-doped porous carbon spheres, carbon black, and PVDF in a mass ratio of 7:1.5:1.5 in NMP and grinding into a uniform slurry, after which the slurry is coated on the copper foil and The working electrode pole piece was obtained by vacuum drying at 80 ° C for 12 h. The dried pole piece is cut into a circular sheet shape and the active material density is 0.5-1 mg cm -2 , and the fresh lithium piece is assembled into a button battery in the glove box, and the electrolyte is 1M LiPF 6 (the solvent is ethylene carbonate) And diethyl carbonate 1:1), Whatman glass fiber membrane is a membrane. The cyclic volt-ampere characteristic curve and the constant capacitance constant current charge and discharge curve of the test battery in the range of 0.01 to 3.0 V vs. Li/Li + were measured. The specific analysis results are as follows:
图1(a)至(f)分别为实施例1得到的硼掺杂多孔碳球扫描电镜、透射电镜及元素分布图。扫描电镜能够看出硼掺杂多孔碳球包含大量50~400nm的球形颗粒,透射电镜图像能够看出单个球体内部分布均匀着大量微孔结构,进一步分析可知这些孔隙尺寸在2nm左右。元素分布图中能够看出实施例1得到的硼掺杂多孔碳球内C、B、O均匀分布,成功证明了硼元素的原位、均匀掺杂。1(a) to (f) are respectively a boron-doped porous carbon sphere scanning electron microscope, a transmission electron microscope, and an element distribution diagram obtained in Example 1. Scanning electron microscopy showed that the boron-doped porous carbon spheres contained a large number of spherical particles of 50-400 nm. The transmission electron microscopy images showed that a large number of microporous structures were uniformly distributed inside the single sphere. Further analysis showed that these pore sizes were around 2 nm. In the elemental distribution diagram, it can be seen that the C, B, and O in the boron-doped porous carbon sphere obtained in Example 1 are uniformly distributed, and the in-situ and uniform doping of the boron element is successfully demonstrated.
图2为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的拉曼光谱。能够看出实施例1得到的硼掺杂多孔碳球相比于实施例1得到的未掺杂多孔碳球具有更强的G峰,证明了硼掺杂大大提高了碳材料的石墨化度。2 is a Raman spectrum of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1. It can be seen that the boron-doped porous carbon sphere obtained in Example 1 has a stronger G peak than the undoped porous carbon sphere obtained in Example 1, demonstrating that boron doping greatly improves the degree of graphitization of the carbon material.
图3为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的N2吸附等温线。能够看出实施例1得到的硼掺杂多孔碳球呈现分级孔结构特征,而对比实施例1得到的未掺杂多孔碳球为微孔型材料,说明硼掺杂拓宽了碳材料的孔隙范围,分级孔隙结构将有利于电化学扩散及反应过程。对吸附等温线分析可知实施例1得到的硼掺杂多孔碳球比表面积1551m2g-1,孔容为1.35cm2g-1。3 is an N2 adsorption isotherm of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1. It can be seen that the boron-doped porous carbon sphere obtained in Example 1 exhibits a hierarchical pore structure characteristic, and the undoped porous carbon sphere obtained in Comparative Example 1 is a microporous material, indicating that boron doping broadens the pore range of the carbon material. The hierarchical pore structure will facilitate electrochemical diffusion and reaction processes. The adsorption isotherm analysis revealed that the boron-doped porous carbon sphere obtained in Example 1 had a specific surface area of 1551 m 2 g -1 and a pore volume of 1.35 cm 2 g -1 .
图4为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球在空气气氛下的失重曲线,能够明显看出硼掺杂后失重温度上移了近150℃,证明硼掺杂大大提高了碳材料的热稳定性。4 is a graph showing the weight loss curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1 in an air atmosphere, and it can be clearly seen that the weight loss temperature after boron doping is shifted upward by nearly 150. °C, demonstrating that boron doping greatly improves the thermal stability of carbon materials.
图5为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的X射线光电子能谱(XPS)分峰曲线。能够明显看出对比实施例1得到的未掺杂多孔碳球
没有硼元素信号,而实施例1得到的硼掺杂多孔碳球具有明显的硼元素信号,而硼的存在状态包括BC3和BC2O两种结构单元。XPS元素含量分析表明实施例1得到的硼掺杂多孔碳球硼掺杂量可达4.25-wt%。5 is a X-ray photoelectron spectroscopy (XPS) peak curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1. The undoped porous carbon sphere obtained in Comparative Example 1 can be clearly seen.
There is no boron element signal, and the boron-doped porous carbon sphere obtained in Example 1 has a distinct boron element signal, and the existence state of boron includes two structural units of BC3 and BC2O. XPS element content analysis showed that the boron-doped porous carbon sphere boron doping amount obtained in Example 1 was up to 4.25-wt%.
图6为实施例1得到的硼掺杂多孔碳球组成的锂离子电池在0.2mV s-1扫速下的循环伏安特性曲线,体现了典型碳材料的特征,首圈容量较大,经过两次循环后保持稳定,这是因为SEI层的形成。6 is a cyclic voltammetric characteristic curve of a lithium ion battery composed of boron-doped porous carbon spheres obtained in Example 1 at a sweep speed of 0.2 mV s -1 , which embodies the characteristics of a typical carbon material, and has a large capacity in the first turn. It remained stable after two cycles due to the formation of the SEI layer.
图7为实施例1得到的硼掺杂多孔碳球组成的锂离子电池在0.2A g-1电流密度下的恒电流充放电曲线,与图6中循环伏安曲线对应,首圈容量较大,经过两次循环后保持稳定,首圈放电容量可达1934mAh g-1,经过50次循环后容量稳定在1160mAh g-1,是商用石墨材料的3倍左右。7 is a graph showing a constant current charge and discharge curve of a lithium ion battery composed of boron-doped porous carbon spheres obtained in Example 1 at a current density of 0.2 A g -1 , corresponding to the cyclic voltammetry curve of FIG. After two cycles, it remains stable. The first ring discharge capacity can reach 1934mAh g -1 . After 50 cycles, the capacity is stable at 1160mAh g -1 , which is about 3 times that of commercial graphite material.
图8为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的倍率性能曲线,能够看出,实施例1得到的硼掺杂多孔碳球较未掺杂多孔碳球表现出优异的倍率性能,在高电流密度10A g-1仍有374mAh g-1的容量。8 is a rate performance curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1. It can be seen that the boron-doped porous carbon sphere obtained in Example 1 is less blended. The heteroporous carbon spheres exhibit excellent rate performance and still have a capacity of 374 mAh g -1 at a high current density of 10 A g -1 .
图9为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的在0.2A g-1电流密度下的循环稳定性曲线。180次循环期间,硼掺杂多孔碳球容量几乎无衰减,仍保持1062mAh g-1。Fig. 9 is a cycle stability curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1 at a current density of 0.2 A g -1 . During the 180 cycles, the boron-doped porous carbon spheres had almost no attenuation and remained at 1062 mAh g -1 .
图10为实施例1得到的硼掺杂多孔碳球和对比实施例1得到的未掺杂多孔碳球的在大电流密度5A g-1下的循环稳定性曲线。随循环次数增强,硼掺杂多孔碳球锂离子储存容量呈现逐渐上升趋势,这是由于多孔炭材料电化学反应过程的活化作用,2000次循环后容量为502mAh g-1。相比而言,对比实施例1得到的未掺杂多孔碳球在循环到1000次电池短路。充分证明了硼掺杂后对增强碳结构循环稳定性的作用。10 is a cycle stability curve of the boron-doped porous carbon sphere obtained in Example 1 and the undoped porous carbon sphere obtained in Comparative Example 1 at a large current density of 5 A g -1 . With the increase of the number of cycles, the storage capacity of boron-doped porous carbon spheres has a gradual upward trend. This is due to the activation of the electrochemical reaction process of porous carbon materials. The capacity after 2,000 cycles is 502 mAh g -1 . In contrast, the undoped porous carbon spheres obtained in Comparative Example 1 were short-circuited to 1000 cycles. The effect of boron doping on the stability of the carbon structure cycle is fully demonstrated.
应当注意的是,本发明的实施例有较佳的实施性,且并非对本发明作任何形式的限制,任何熟悉该领域的技术人员可能利用上述揭示的技术内容变更或修饰为等同的有效实施例,但凡未脱离本发明技术方案的内容,依据本发明的技术实质对以上实施例所作的任何修改或等同变化及修饰,均仍属于本发明技术方案的范围内。
It should be noted that the embodiments of the present invention are preferred embodiments, and are not intended to limit the scope of the present invention. Any one skilled in the art may use the above-disclosed technical contents to change or modify the equivalent embodiments. Any modification or equivalent changes and modifications of the above embodiments in accordance with the technical spirit of the present invention are still within the scope of the technical solutions of the present invention.